1. Field of Invention
This is a motor vehicle safety device that warns of vehicles in the driver's blind-spot.
2. Prior Art
Drivers of motor vehicles should be aware of other nearby vehicles, particularly when they are changing lanes on a multilane highway. Rearview mirrors, required safety equipment for automobiles, address the need drivers have to monitor the traffic situation behind them. Some drivers have difficulty making adequate use of their rearview mirrors. One problem arises when another vehicles is close to them in an adjacent lane, slightly behind the driver's vehicle, so the nearby vehicle is not visible in the inside rearview mirror and is not visible in the driver's peripheral vision when the driver is looking straight ahead. This is the so-called blind-spot problem. Another related problem is that some drivers do not check their rearview mirror every few seconds to continually update their knowledge about the traffic situation behind them. These problems become worse when distractions, such as cell phone conversations or disruptive children, compete for the driver's attention. These problems also worsen when long trips fatigue drivers.
Traffic safety experts and people working in the automobile industry recognize the blind-spot problem. Systems have been developed, in addition to rearview mirrors, to address this problem. Typical prior-art systems, represented by U.S. Pat. No. 6,388,565, have sensors, signal processing, and a driver interface. These three elements in the prior art systems have problems what retard widespread use. The sensors are typically technically advanced and sophisticated devices such as radar or ultrasound. These technically sophisticated sensors are generally expensive, which is a problem for widespread deployment. Another disadvantage of technically sophisticated sensors is that they generally require technically sophisticated signal processing. For a system that uses, for example, radar, the signal processing must either determine when a vehicle is in the blind-spot, or it must present data that will allow the driver to determine a blind-spot presence. Making a safety system responsible for interpreting the sensor data for the driver is risky. False warning mistakes annoy the driver, and mistakes of missed vehicles are dangerous. Different cases that need to be considered make interpretation difficult. For example, the system will detect cars in the blind spot when stuck in traffic jams or when in a city; but warnings sent to the driver in these situations might be unwelcome. The interface to the driver is typically a warning such as a flashing light, a sound, or a vibration that the driver feels. The interface must provide a positive warning to the driver without annoying the driver. An interface that is helpful without being annoying is difficult.
The present invention uses tire noise of nearby vehicles to give blind-spot warnings. U.S. Pat. No. 3,158,835 has many elements of the present invention. However, anyone implementing the system taught by U.S. Pat. No. 3,158,835 would find that the sounds presented by the system that originate from the host vehicle would limit usefulness of the system. U.S. Pat. No. 3,158,835 does not adequately teach how to discriminate between the sounds from the host vehicle and the useful sounds of nearby vehicles. Perhaps because sources of constant noise are annoying, there are no known direct descendants of U.S. Pat. No. 3,158,835, and it has not been developed into an available product. The philosophy of quieting host noise to enhance the usefulness of environmental noise for safety is shown in U.S. Pat. No. 6,325,173 that shows the use of wind screens in front of bicyclists' ears so they can better hear overtaking cars. The car safety invention described here differs from the bicycle windscreen patent because it teaches how to make useful sounds available to someone operating a vehicle inside a sound-blocking enclosure.
Another prior art, U.S. Pat. No. 4,943,798 and similar patents, uses many of the same elements of this invention but for the purpose of monitoring the mechanical health of remote tires and wheels on tractor trailer trucks.
Another prior art, U.S. Pat. No. 5,278,553, uses microphones outside a car. This patent teaches how to warn a deaf driver, or a driver listening to a loud sound system, when an emergency vehicle's siren is sounding nearby. The purpose of this patent, the nature of the signal processing, and the interface to the driver are all different from the present invention.
The near absence of prior art blind-spot warning systems that use tire noise is striking. This absence is due in part to basic goals and assumptions that guide the automotive industry. Modern automobiles are quiet inside. They are designed to block road or tire noise, and wind noise. Most people judge quiet cars to be good, and quieter cars to be better. The ability to keep passenger compartments quiet has been aided by the widespread use of automobile air conditioners so windows often remain closed in all types of weather, particularly at highway speeds. The automobile industry considers road noise, in particular, to be a nuisance with no redeeming value. The use of road noise as a useful and interesting sensual input is a paradigm shift for the automotive industry. This helps explain why the use of tire noise to alert drivers to vehicles in their blind-spot has not been pursued by the automotive industry, but instead was demonstrated by a bicycle rider who was able to build a demonstration in his basement from inexpensive components.
Objects and Advantages
This invention alerts a driver to vehicles in his blind spots by allowing the driver to hear nearby vehicles. Another object of this invention is to help drivers to be more alert by making driving a more sensually rich experience. Another object of this invention is to not annoy drivers with useless noise. A further object of this invention is to make driving more interesting.
This invention can be implemented with inexpensive hardware. The sensors are electret microphones in one demonstration implementation. The signal processing is relatively simple because this system does not make any decisions concerning the need to warn the driver about blind-spot intrusions. The data is presented to the driver without interpretation. The driver provides the interpretation function. Also, the signal processing need use only audio frequency signals, which are easy to manipulate.
The interface is straightforward. The driver hears sounds that seem to come from nearby vehicles. The sounds actually come from inexpensive loudspeakers. These sounds resemble the sounds that would be heard from nearby vehicles if the noise-blocking passenger compartment were not in the way. A driver using this system does not perceive any increase in wind noise or tire noise coming from his vehicle. The sounds from this safety system are of much higher quality, that is, free from extraneous noise, than what a driver would hear if she opened her windows at highway speeds. Drivers find the sounds made by this system, which seem to come from the highway environment, easy to interpret, useful, and interesting.
This system does not noticeably add objectionable noise to the passenger compartment. By using directionally selective microphones and electronic signal processing that exploits the directional properties of the microphones, the system essentially rejects noise coming from the host vehicle. The only sounds that the driver notices coming from the safety system are useful sounds from nearby vehicles.
The data interpretation function is done by the driver. This is an important point that makes this system superior to the prior art represented by U.S. Pat. No. 6,388,565. People are extremely good at interpreting sounds from activities happening close to them, when the sounds are not blocked by an enclosure. This ability to interpret sounds is built into people's neurological system. It operates naturally and it operates unconsciously, that is, without conscious effort. New sounds coming from behind have a high priority ability to focus attention. To say this another way, new sounds coming from behind are automatically considered to be very important by primitive parts of the human brain. This ability does not need to be learned. The ability to accurately and automatically interpret sounds that correspond to environmental situations is shared by many animals. This remarkable ability is the result of millions of years of evolution. The vehicle safety system described here makes use of this ability.
Another advantage of this invention is that drivers find that using this device is interesting. Drivers appreciate the additional sensual inputs provided, not only for the safety benefit, but because the sounds make driving more fun. Being able to hear clearly what is happening nearby is a welcome, natural ability enjoyed by people who have normal hearing, and sadly missed by people who are hearing impaired. No one, for example, would consider wearing ear plugs while making love, except perhaps if they had been married for thirty years. People enjoy the sounds from this system because they mitigate the aural sensory deprivation caused by modern, sound-insulated cars.
One benefit of the sounds provided by this system being interesting is that drivers do not need to be encouraged or coerced to use the system. They enjoy using the system.
Another benefit of this invention is that because driving is more interesting when drivers can hear what is happening around them, drivers stay more alert and better focused on their driving tasks on long trips.
The sounds produced by this safety system need not interfere with traditional in-car activities. The driver has no difficulty conversing with passengers or listening to the car radio while using this system. Passengers are barely aware of the system's presence.
Microphones have advantages as sensors. They are inexpensive, the required signal processing for use in blind-spot warnings is simple, and microphones are adequate to do an excellent job for automobiles. However, there are applications for which passive microphones have limitations and for which cost is not a major concern. One example is a system to warn a pilot of nearby aircraft. The advantages of an interface that mimics natural sound could be combined with radar sensors, or any sensors that can detect objects and estimate their location.